Calm those getting upset about nothing (6)
I believe the answer is:
soothe
'calm' is the definition.
(I've seen this before)
'those getting upset about nothing' is the wordplay.
'getting upset' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'nothing' becomes 'O' (looks like zero - 0).
'those' anagrammed gives 'sothe'.
'sothe' going around 'o' is 'SOOTHE'.
(Other definitions for soothe that I've seen before include "Cause to feel better" , "Assuage, calm" , "Console, pacify" , "'Console, comfort (6)'" , "Appease" .)